This application relates to photoactivatable silane compounds, methods of making photoactivatable silane compounds, and methods for use of photoactivatable silane compounds as silylating agents in the treatment of surfaces, such as glass.
Silylating agents have been developed in the art which react with and coat surfaces, such as silica surfaces. For example, silylating agents for use in modifying silica used in high performance chromatography packings have been developed. Monofunctional silylating agents have been used to form monolayer surface coatings, while di- and tri-functional silylating agents have been used to form polymerized coatings on silica surfaces. Many silylating agents, however, produce coatings with undesirable properties including instability to hydrolysis and the inadequate ability to mask the silica surface which may contain residual acidic silanols.
Recently, a method has been reported for grafting polystrene films to glass surfaces using a photoactivatable silane. Prucker et al., J. Am. Chem. Soc. 121:8766 (1999). The system is based on a photoreactive benzophenone derivative that is bound to SiO2 surfaces via a silane anchor.
In one aspect of the invention, photoactivatable silane compounds and methods for their synthesis and use are provided. In one embodiment, the photoactivatable silane compounds synthesized are represented by a structural formula: PG-LS-SN, wherein PG is a photoactivatable group, LS is a linkage and spacer group, and SN is a silane group. The silanes allow the photoactivatable silane compounds to be covalently bound to the surface of a substrate such as silica. A linkage and spacer joins the silane to the photoactivatable group. The photoactivatable group forms a hydrophobic layer that can be photochemically cross-linked with a layer of hydrophilic functional polymers.
In another embodiment, a method is disclosed to synthesize a substrate of hydrophobic layers and hydrophilic functional polymer layers thereafter onto glass surfaces. The photoactivatable silane compounds are synthesized and bound to the surface of a substrate such as silica. Hydrophilic polymers with reactive functional groups are applied to the substrate, and then photochemically cross-linked to the hydrophobic layers to form a functionalized surface with a plurality of functional groups on the polymer.
In yet another embodiment, after forming of a functionalized surface on the surface of a substrate, an array of biopolymers such as nucleic acids may be covalently attached to the substrate using photolithography and DNA synthesis. The method permits the formation of high density arrays of nucleic acids immobilized on a substrate, which may be used, for example, in conducting high volume nucleic acid hybridization assays.
In a further embodiment, a benzophenone-based silane is synthesized and used to prepare stable, hydrophobic, photoactivatable coatings on solid supports. Hydrophilic polymers are then applied to the substrate, and photochemically cross-linked to the underlying silane. The resulting substrates are suitable for fabricating oligonucleotide probe arrays either by in situ synthesis or immobilization methods.